Column No to Column Letter in Excel/VSTO using C#

Question

How to find column's name or header?

For example if i select column 5 in excel means i want the result as "E". How to get the alphabet or letter corresponding to column no.

Please help me with the code

Answer 1

public static string GetColumnName(int columnNumber)
{
    const string letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    string columnName = "";

    while (columnNumber > 0)
    {
        columnName = letters[(columnNumber - 1) % 26] + columnName;
        columnNumber = (columnNumber - 1) / 26;
    }

    return columnName;
}

Answer 2

What about using Application.ActiveCell.get_Address(true, true, Excel.AlReferenceStyle.xlA1, missing, missing) and then parse the result string or use a RegEx to get the column heading?

I simply used:

string location = Application.ActiveCell.get_Address(true, true, Excel.AlReferenceStyle.xlA1, missing, missing);
string tokens = x.Split("$".ToCharArray());
MessageBox.Show(String.Format("Column {0}", result[0]));

Answer 3

public static long GetColumnNumber(string columnName)
{
    int letterPos = 0;   
    long columnNumber = 0;
    for (int placeHolder = columnName.Length - 1; placeHolder >= 0; placeHolder--)
    {
        int currentSum = 1;
        for (int multiplier = 0; multiplier < placeHolder; multiplier++)
            currentSum *= 26;
        int letterValue = (int) columnName[letterPos];
        currentSum *= letterValue - 64;
        columnNumber += currentSum;
        if (letterPos != columnName.Length)
            letterPos++;
        //Console.WriteLine(((int)columnName[i]-64) + " = " + columnName[i]);
    }
        return columnNumber;
}